I mean this is just ONE part of what you need! This is truly insane!!
Flightstones are an item used in Dragonflight Season 2 to upgrade PvE gear (along with Shadowflame Crests). Flightstones are required for all PvE item upgrades, from Explorer 1/8 (i376) to Hero 5/5 (i441). Generally speaking, the higher the item level you are upgrading, the more flightstones you will need to use, however the actual cost also depends on the item being upgraded, with weapons requiring the most. Flightstones have no weekly or seasonal cap, but you can only hold up to 2,000 per character at any one time, and they can not be traded between characters. Flightstones come from almost all Season 2 PvE content, including Treasures, Quests, World Quests, Rares, Rare Elites, Weekly Bosses, Fyrakk Assaults, Dungeons, Mythic+ and Raids, with harder content rewarding more flightstones.
Item upgrades in Season 2 have an Account-Wide discount - for a given item slot, if you upgrade a new item at a lower item level than you’ve previously upgraded for that slot, you will only need to pay 50% of the cost of the upgrade. For example, if you already have a belt - [Drogbar Girdle of Great Lifting] which dropped at Veteran 2/8 (i405), and you upgraded it to Veteran 7/8 (i421) before [Drogbar Belt of the Wonderous Winner’s Enclave] dropped at Champion 1/8 (i415), you can upgrade the new belt up to Champion 3/8 (i421) for 50% of the Flightstone cost that it would’ve taken if you didn’t upgrade the initial item, as well as not costing Shadowflame Crests. If the item dropped for a different character on your account, the Flightstone discount would still apply, however you would need to use Shadowflame Crests if the upgrade required it. For slots with two items (Rings, Trinkets and Weapons), the lower level of the two items is the one that counts for the purposes of upgrade discounts.
Finally, Flightstones are also used for upgrading crafted gear. You can buy an Empowered Flightstone from Dustmonger Topuiz for 150 Flightstones, which can be combined with an Enchanted Shadowflame Crest to upgrade a crafted item to between i395 and i447, depending on the rank of Shadowflame Crest.
What an abomination!